Sponge rubber mold



Jan. 25, 1944. c. F. supMAN 2,340,278

SPONGE RUBBER MOLD Filed Oct. 5. 1940 j 1 vue-14401,

Char/e5 50a/maiz amounted to as much as 5% Patented Jan. 25, 1944 2,340,211; sroNGE RUBBER. MOLD Charles F.

tion of Delaware Application October 3. 1940, Serial No.

Sudman, Akron, Ohio, assignor. to Wingfoot Corporation, Akron,

Ohio, a corporaz claims. (ci. 11i-s4) A This invention relates to a new type of mold for sponge rubber. It includes a mold with an be the drawing.v

The invention includes a mold with an insert which excludes the roamed latex from around a part of the lugs fastened to the cover of the mold. and it also includes a new design of mold which avoids the necessity of providing the usual vent holes in the mold cover.

brought into place,

The vent holes have been considered necessary. c although their use involves various disadvantages.

It has been customary to exude through these vent holes and form what are known as pips. In removing the sponge rubber from the molds the pips often are held by the mold cover and cause the rubber to tear, leaving Furthermore, the loss of rub-- ber in the formation of the plps has in the past of the total latex employed. The elimination vided in the present invention therefore is a decided advance in the art.-

The invention will be further described in connection with the accompanying drawing which is an elevation in section through a cushion mold, although, of course, the invention is not limited to cushion molds. The mold cover l is of the usual type andis provided with one or more vent holes 2 within the space included by the insert plate 3 and also vent holes l outside of this area which perform their usual function. The bottom of the mold 5 which forms the smooth surfaced top of the cushion 6 is supported by the usual angle bowl supports 1.

In order to reduce the amount of latex rg'equired for the formation of the sponge rubber cushion the sheet metal insert 3 is inserted as shown to form a cup-shaped hollow in the bottom of the cushion. This insert is fastened to the cover i by self-tapping screws 8.

The mold is provided with the usual lugs 9 which are fastened to the cover by the cap screws i0. Instead of providing special short lugs to be fastened to the insert plate 3, lugs of the usual size 9 (which are not y.necessarily all of the same length) are used and openings I2 to cause the' foamed latex of these pips as prothe insert 3.

v through an opening which is escape of foamed latex.

Applying the same principle of venting to the ordinary mold (i. e.,.a mold 3), it will be seen areprovided in the insert through whin theK ings 9 project into the foamed latex.

To use this mold the bowl 5 is lled with the required amount of foamed latex. which may be produced by anyA of theusual methods. The cover is then placed over the bowl as shown. No closing means are necessary. The weight of the cover is suflicient to keep the bowl closed. Dowels or other pins may be used to prevent lateral displacement.

The openings l! in the insert plate 3 around 4the lugs 8 provide a clearance suflicient to'permit the escape of entrapped air as the cover is but too small for the passage of the foamed latex. A clearance of about .002 to around .005 inch will usually be suitable, although the maximum permissible will depend upon the consistency of the foamed latex. These v openings l2 around the lugs therefore provide for venting the air without the formation of pips. Ihe openings, being around the lugs,are in the best possible location for the removal of entrapped air, .because apparently the air surfaces of the lugs and is therefore readily vented through these openings. No vent holes of the usual type are required in the insert 3. To provide for the removal oi air from within the hollow formed above the insert, one vor more vent holes 2 are provided in th'e cover plate. The vent holes 4 outside of the area included within the insert 3 vent the air in the usual fashion.

The design of the mold may be improved and the vents l may be eliminated by providing a vent hole around each of the lugs 9 which are located outside of that portion of the cover enclosed -by Each of these openings may be similar to the openings l2 around the lugs surrounded by the insert 3. The openings should provide a clearance suiliciently small to prevent the passage of the latex therethrough. The maximum clearance permissible will depend upon the thickness of the latex. In general the clearance should be no greater than about 0.005 inch. To accomplish this the lug 8 may be inserted through the cover plate instead of being fastened to it -bya cap screw, may be a few thousandths oran inch .larger in diameter than the diameter ofthe lug. The lug may be held in this opening in any suitable manner to provide ior venting the air around the lug too small for the without the insert that the usual vent holes may rises along the and the opening in the cover plate be omitted en through the c 1t in such a w ing passage which is too small to permit passage or the foamed latex the passage o! the latex. 5 therethrough.

'I'he mold is provided with the usual register 2. In a mold for sponge rubber, a cover, an into make sure that the necessary amount of sert plate fastened to the cover of the mold roamed latex is added to it. adapted to form a hollow in the bottom of the What I claim is: sponge rubber product formed in the mold, and

1. In a mold for sponge rubber, a cover, an n- 10 lugs fastened to the cover of the mold and passsert plate fastened to the cover of the mold ing through openings provided therefor in the adapted to form a. hollow in the bottom of the insert. sponge rubber product formed in the mold, a lug CHARLES F. SUDMAN. 

